This is an ongoing prospective study to determine the efficacy of hearing conservation in patients with endolymphatic hydrops (Meniere's disease) following endolymphatic sac decompression and drainage surgery. In addition, subjective and objective data about all patients screened is placed on computer for multivariable statistical analysis. The value of the provocative glycerol test, as a diagnostic tool for endolymphatic hydrops, is being evaluated with very promising results. Biopsies of the endolymphatic sac epithelium are being studied at the light and ultrastructural levels to determine the pathogenesis of the inner ear fluid imbalance. The results of 35 endolymphatic sac decompression and drainage procedures to conserve hearing have been analyzed with over 50% significant improvements in hearing, 20% stabilized hearing and 84% complete relief of vertigo. This analysis at the 3rd year is most encouraging; however, the remaining follow-up time and additional patients would help to definitely answer the primary question proposed by this study, i.e., if conservation of hearing surgery is done early in the course of the disease - will it alter the natural progressive course of the hearing impairment.